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authorHeiko Carstens <hca@linux.ibm.com>2022-02-23 13:02:59 +0100
committerVasily Gorbik <gor@linux.ibm.com>2022-03-01 20:41:28 +0100
commit9fa881f7e3c74ce6626d166bca9397e5d925937f (patch)
tree7197c2dd10105a8244fa2258931d943bb462fc87 /arch/s390
parent6b4b54c7ca347bcb4aa7a3cc01aa16e84ac7fbe4 (diff)
s390/ftrace: fix ftrace_caller/ftrace_regs_caller generation
ftrace_caller was used for both ftrace_caller and ftrace_regs_caller, which means that the target address of the hotpatch trampoline was never updated. With commit 894979689d3a ("s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations") a separate ftrace_regs_caller entry point was implemeted, however it was forgotten to implement the necessary changes for ftrace_modify_call and ftrace_make_call, where the branch target has to be modified accordingly. Therefore add the missing code now. Fixes: 894979689d3a ("s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations") Reviewed-by: Sven Schnelle <svens@linux.ibm.com> Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/kernel/ftrace.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 21d62d8b6b9a..5026d218066d 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -159,9 +159,38 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
return 0;
}
+static struct ftrace_hotpatch_trampoline *ftrace_get_trampoline(struct dyn_ftrace *rec)
+{
+ struct ftrace_hotpatch_trampoline *trampoline;
+ struct ftrace_insn insn;
+ s64 disp;
+ u16 opc;
+
+ if (copy_from_kernel_nofault(&insn, (void *)rec->ip, sizeof(insn)))
+ return ERR_PTR(-EFAULT);
+ disp = (s64)insn.disp * 2;
+ trampoline = (void *)(rec->ip + disp);
+ if (get_kernel_nofault(opc, &trampoline->brasl_opc))
+ return ERR_PTR(-EFAULT);
+ if (opc != 0xc015)
+ return ERR_PTR(-EINVAL);
+ return trampoline;
+}
+
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr)
{
+ struct ftrace_hotpatch_trampoline *trampoline;
+ u64 old;
+
+ trampoline = ftrace_get_trampoline(rec);
+ if (IS_ERR(trampoline))
+ return PTR_ERR(trampoline);
+ if (get_kernel_nofault(old, &trampoline->interceptor))
+ return -EFAULT;
+ if (old != old_addr)
+ return -EINVAL;
+ s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
return 0;
}
@@ -188,6 +217,12 @@ static void brcl_enable(void *brcl)
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
+ struct ftrace_hotpatch_trampoline *trampoline;
+
+ trampoline = ftrace_get_trampoline(rec);
+ if (IS_ERR(trampoline))
+ return PTR_ERR(trampoline);
+ s390_kernel_write(&trampoline->interceptor, &addr, sizeof(addr));
brcl_enable((void *)rec->ip);
return 0;
}